Kaleidoscope UK's two albums called Tangerine Dream and Faintly Blowing are also worth checking too. The whole of Faintly Blowing and most of Tangerine Dream are available very cheaply on the Dive Into Yesterday CD anthology, highly recommended if you like the first Pink Floyd
if you like piper at the gates of dawn try to find pretties for you by alice cooper, you love it gaurenteed.